Depth sensing method, 3D image generation method, 3D image sensor, and apparatus including the same

Abstract

A three-dimensional (3D) image sensor module including: an oscillator configured to output a distortion-compensated oscillation frequency as a driving voltage of a sine wave biased with a bias voltage; an optical shutter configured to vary transmittance of reflective light reflected from a subject, according to the driving voltage, and to modulate the reflective light into at least two optical modulation signals having different phases; and an image generator configured to generate image data about the subject, the image data including depth information that is calculated based on a difference between the phases of the at least two optical modulation signals.

What is claimed is: 
     
       1. A three-dimensional (3D) image sensor module comprising:
 an oscillator configured to output a distortion-compensated oscillation frequency as a driving voltage of a sine wave that is biased with a bias voltage; 
 an optical shutter configured to:
 receive the output driving voltage from the oscillator; and 
 vary transmittance of reflective light that is reflected from a subject, based on the received driving voltage, to modulate the reflective light into at least two optical modulation signals having different phases; 
 
 an image sensor configured to receive, from the optical shutter, the at least two optical modulation signals into which the reflective light is modulated; and 
 an image processor configured to generate image data of the subject, the image data comprising depth information that is determined based on a difference between the different phases of the received at least two optical modulation signals, 
 wherein the oscillator comprises:
 a resonator configured to resonate via an energy exchange with the optical shutter to generate the driving voltage; 
 an energy supplementer configured to supply, to the resonator, replacement energy corresponding to an amount of energy lost during the energy exchange between the resonator and the optical shutter; and 
 a distortion compensator configured to compensate for a distortion of the replacement energy supplied by the energy supplementer to the resonator. 
 
 
     
     
       2. The 3D image sensor module of  claim 1 , wherein the distortion compensator is connected to the energy supplementer so that the distortion compensator is further configured to prevent the energy supplementer from blocking the driving voltage from swinging to a negative value. 
     
     
       3. The 3D image sensor module of  claim 1 , wherein the optical shutter comprises a first end and a second end, and
 the resonator comprises:
 an inductor comprising a first end connected to the first end of the optical shutter, and a second end; and 
 a capacitor comprising a first end connected to the second end of the inductor, and a second end connected to the bias voltage and the second end of the optical shutter. 
 
 
     
     
       4. The 3D image sensor module of  claim 3 , wherein the energy supplementer is further configured to supply energy to the capacitor via the inductor when energy is exchanged between the capacitor and the optical shutter. 
     
     
       5. The 3D image sensor module of  claim 3 , wherein the energy supplementer comprises:
 a first switching element comprising a first end connected to a power supply terminal, a second end connected to the first end of the inductor, and a gate connected to the second end of the inductor, the first switching element being configured to be switched by a voltage on the second end of the inductor; 
 a second switching element comprising a first end connected to the power supply terminal, a second end connected to the second end of the inductor, and a gate connected to the first end of the inductor, the second switching element being configured to be switched by a voltage on the first end of the inductor; 
 a third switching element comprising a first end connected to the first end of the inductor, a second end, and a gate connected to the second end of the inductor, the third switching element being configured to be switched by the voltage on the second end of the inductor; and 
 a fourth switching element comprising a first end connected to the second end of the inductor, a second end connected to the second end of the third switching element, and a gate connected to first end of the inductor, the fourth switching element being configured to be switched by the voltage on the first end of the inductor. 
 
     
     
       6. The 3D image sensor module of  claim 5 , wherein the first switching element and the fourth switching element are configured to, when energy is moved from the capacitor to the optical shutter via the inductor, be turned on to supply energy to the capacitor, and
 the second switching element and the third switching element are configured to, when energy is moved from the optical shutter to the capacitor via the inductor, be turned on to supply energy to the capacitor. 
 
     
     
       7. The 3D image sensor module of  claim 5 , wherein the first switching element and the second switching element comprise respective p-type metal-oxide-semiconductor (PMOS) transistors, and
 the third switching element and the fourth switching element comprise respective n-type metal-oxide-semiconductor (NMOS) transistors. 
 
     
     
       8. The 3D image sensor module of  claim 5 , wherein the distortion compensator comprises at least one resistor comprising a first end connected to the second end of the third switching element and the second end of the fourth switching element, and second end connected to a ground terminal, and
 the distortion compensator is further configured to balance a mismatch between driving capabilities of the third switching element and the fourth switching element. 
 
     
     
       9. The 3D image sensor module of  claim 5 , wherein the distortion compensator comprises:
 a first compensator comprising a first end connected to the first end of the inductor, and a second end: and 
 a second compensator comprising a first end connected to the second end of the inductor, and a second end, 
 the first end of the third switching element is connected to the second end of the first compensator to connect to the first end of the inductor via the first compensator, and 
 the first end of the fourth switching element is connected to the second end of the second compensator to connect to the second end of the inductor via the second compensator. 
 
     
     
       10. The 3D image sensor module of  claim 9 , wherein the first compensator comprises a first diode configured to supply a current from the first end of the inductor to the third switching element, and
 the second compensator comprises a second diode configured to supply a current from the second end of the inductor to the fourth switching element. 
 
     
     
       11. The 3D image sensor module of  claim 1 , wherein the oscillator further comprises a burst mode driver configured to output a burst signal indicating that the 3D image sensor module is operating in a burst mode, and
 the energy supplementer is further configured to, in response to receiving the burst signal, interrupt the supply of the replacement energy to the resonator. 
 
     
     
       12. The 3D image sensor module of  claim 1 , further comprising a first controller configured to detect the output driving voltage to generate a control signal,
 wherein the oscillator is further configured to control the supply of the replacement energy to the resonator, based on the control signal. 
 
     
     
       13. The 3D image sensor module of  claim 1 , further comprising:
 a temperature sensor configured to sense a temperature of the 3D image sensor module, and generate temperature information, based on the sensed temperature; and 
 a controller configured to generate a control signal, based on the temperature information, 
 wherein the oscillator is further configured to control the supply of the replacement energy to the resonator, based on the control signal. 
 
     
     
       14. The 3D image sensor module of  claim 1 , further comprising:
 a memory configured to store feature information corresponding to operational features of the 3D image sensor module; and 
 a controller configured to generate a control signal, based on the feature information, 
 wherein the oscillator is further configured to control the supply of the replacement energy to the resonator, based on the control signal. 
 
     
     
       15. The 3D image sensor module of  claim 1 , wherein the optical shutter comprises:
 a first electrode to which the output driving voltage is to be supplied; 
 a second electrode to which the output driving voltage is to be supplied; 
 a first semiconductor layer disposed between the first electrode and the second electrode; 
 a second semiconductor layer disposed between the first electrode and the second electrode; and 
 a multiple quantum well disposed between the first semiconductor layer and the second semiconductor layer, and 
 the first electrode, the first semiconductor layer, the multiple quantum well, the second semiconductor layer, and the second electrode are layered in order. 
 
     
     
       16. The 3D image sensor module of  claim 1 , wherein the optical shutter is further configured to modulate the reflective light into four optical modulation signals having phases of 0 degrees, 90 degrees, 180 degrees, and 270 degrees, respectively. 
     
     
       17. An apparatus configured to measure the subject, the apparatus comprising the 3D image sensor module of  claim 16 . 
     
     
       18. The 3D image sensor module of  claim 1 , wherein the image sensor is further configured to sense each of the received at least two optical modulation signals, generate an electrical signal corresponding to the sensed at least two optical modulation signals, and output the electrical signal in units of frames, and
 the image processor is further configured to determine the depth information, based on a difference between phases of respective frames of the at least two optical modulation signals. 
 
     
     
       19. The 3D image sensor module of  claim 1 , further comprising a frequency divider configured to divide the oscillation frequency that is received from the oscillator to generate a clock signal,
 wherein the image processor is further configured to generate the image data in synchronization with the clock signal. 
 
     
     
       20. The 3D image sensor module of  claim 1 , further comprising:
 a light source configured to emit incident light beams to the subject; 
 a light source driver configured to drive the light source so that the incident light beams have different phases; 
 a lens configured to focus the reflective light; and 
 a filter configured to filter the focused reflective light, using a same wavelength band as a bandwidth of the incident light beams, and supply a result of the filtering to the optical shutter. 
 
     
     
       21. An electronic apparatus comprising the 3D image sensor module of  claim 1 . 
     
     
       22. The 3D image sensor module of  claim 1  further comprising a plurality of optical shutters. 
     
     
       23. A 3D image sensor module comprising:
 an oscillator comprising a differential LC voltage controlled oscillator (VCO), the differential LC VCO comprising a first end connected to a power supply terminal, and the oscillator being configured to output a distortion-compensated oscillation frequency as a driving voltage of a sine wave that is biased with a bias voltage; 
 an optical shutter configured to:
 receive the output driving voltage from the oscillator; and 
 vary transmittance of reflective light that is reflected from a subject, based on the received driving voltage, to modulate the reflective light into at least two optical modulation signals having different phases; and 
 
 an image sensor configured to:
 receive, from the optical shutter, the at least two optical modulation signals into which the reflective light is modulated; and 
 output at least two electrical signals corresponding to the received at least two optical modulation signals in units of frames, 
 
 wherein the oscillator further comprises:
 a resonator configured to resonate via an energy exchange with the optical shutter to generate the driving voltage; 
 an energy supplementer configured to supply, to the resonator, replacement energy corresponding to an amount of energy lost during the energy exchange between the resonator and the optical shutter; and 
 a distortion compensator configured to compensate for a distortion of the replacement energy supplied by the energy supplementer to the resonator. 
 
 
     
     
       24. The 3D image sensor module of  claim 23 , wherein the optical shutter comprises a first end and a second end, and
 the differential LC VCO comprises:
 an inductor comprising a first end connected to the first end of the optical shutter, and a second end; 
 a capacitor comprising a first end connected to the second end of the inductor, and a second end connected to the bias voltage and the second end of the optical shutter; 
 a first p-type metal-oxide-semiconductor (PMOS) transistor comprising a first end connected to a power supply terminal, a second end connected to the first end of the inductor, and a gate connected to the second end of the inductor, the first PMOS transistor being gated by a voltage on the second end of the inductor; 
 a second PMOS transistor comprising a first end connected to the power supply terminal, a second end connected to the second end of the inductor, and a gate connected to the first end of the inductor, the second PMOS transistor being gated by a voltage on the first end of the inductor; 
 a first n-type metal-oxide-semiconductor (NMOS) transistor comprising a first end connected to the first end of the inductor, a second end, and a gate connected to the second end of the inductor, the first NMOS transistor being gated by the voltage on the second end of the inductor; and 
 a second NMOS transistor comprising a first end connected to the second end of the inductor, a second end connected to the second end of the first NMOS transistor, and a gate connected to first end of the inductor, the second NMOS transistor being gated by the voltage on the first end of the inductor. 
 
 
     
     
       25. The 3D image sensor module of  claim 24 , further comprising:
 a first diode comprising a first end connected to the first end of the inductor, and a second end; and 
 a second diode comprising a first end connected to the second end of the inductor, and a second end, 
 wherein the first end of the first NMOS transistor is connected to the second end of the first diode to connect to the first end of the inductor via the first diode, and 
 the first end of the second NMOS transistor is connected to the second end of the second diode to connect to the second end of the inductor via the second diode. 
 
     
     
       26. The 3D image sensor module of  claim 24 , wherein the differential LC VCO further comprises at least one resistor comprising a first end connected the second end of the first NMOS transistor and the second end of the second NMOS transistor, the at least one resistor being configured to decrease a voltage on the second end of the first NMOS transistor when the driving voltage swings to a negative value, and block a flow of a current from the second end of the first NMOS transistor to the first end of the first NMOS transistor. 
     
     
       27. The 3D image sensor module of  claim 24 , wherein the oscillator further comprises a third NMOS transistor configured to interrupt a power supply to the resonator in response to a burst signal instructing that an operation of the 3D image sensor module be performed in a burst mode. 
     
     
       28. The 3D image sensor module of  claim 27 , wherein the third NMOS transistor is connected between a ground terminal and a current source for supplying a reference current that is a basis for generating a power supply current that is supplied to the power supply terminal, the third NMOS transistor being gated by the burst signal. 
     
     
       29. The 3D image sensor module of  claim 27 , wherein the oscillator further comprises:
 a fourth NMOS transistor connected between the first end of the inductor and a ground terminal, the fourth NMOS transistor being gated by the burst signal; and 
 a fifth NMOS transistor connected between the second end of the inductor and a ground terminal, the fifth NMOS transistor being gated by the burst signal. 
 
     
     
       30. The 3D image sensor module of  claim 23 , further comprising a first controller configured to detect the output driving voltage to generate a control signal,
 wherein the oscillator is further configured to control a supply of energy to the differential LC VCO, based on the control signal. 
 
     
     
       31. The 3D image sensor module of  claim 23 , further comprising a frequency divider configured to divide the oscillation frequency that is received from the oscillator to generate a clock signal,
 wherein the image sensor is further configured to output the received at least two electrical signals in units of frames in synchronization with the clock signal. 
 
     
     
       32. A method of sensing depth information of a subject, the method comprising:
 outputting, by an oscillator, a distortion-compensated oscillation frequency as a driving voltage of a sine wave that is biased with a bias voltage: 
 receiving, by an optical shutter, the output driving voltage from the oscillator; 
 varying, by the optical shutter, a transmittance of reflective light that is reflected from the subject, based on the received driving voltage, to modulate the reflective light into at least two optical modulation signals having different phases; 
 receiving, by an image sensor, the at least two optical modulation signals into which the reflective light is modulated, from the optical shutter; 
 determining, by an image processor, depth information, based on a difference between the different phases of the received at least two optical modulation signals; and 
 generating, by the image processor, image data of the subject, the image data comprising the determined depth information, 
 wherein the outputting comprises:
 resonating, by a resonator, via an energy exchange with the optical shutter to generate the driving voltage; 
 supplying, by an energy supplemener, to the resonator, replacement energy corresponding to an amount of energy lost during the energy exchange between the resonator and the optical shutter; and 
 compensating, by a distortion compensator, for a distortion of the replacement energy supplied by the energy supplementer to the resonator. 
 
 
     
     
       33. The method of  claim 32 , further comprising:
 generating, by the oscillator, the distortion-compensated oscillation frequency as the driving voltage of the sine wave biased with the bias voltage; and 
 generating, by a frequency divider, a clock signal by dividing the oscillation frequency, 
 wherein the determining of the depth information comprises determining, by the image processor, the depth information in synchronization with the clock signal.